Re: [syzbot] [bluetooth?] general protection fault in l2cap_sock_recv_cb

Edward Adam Davis
2024-06-11T03:07:00Z

please test null ptr defref in l2cap_sock_recv_cb

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git cc8ed4d0a848

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 6db60946c627..c0072f81e81a 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1486,6 +1486,14 @@ static int l2cap_sock_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
int err;

lock_sock(sk);
+ sock_hold(sk);
+ l2cap_chan_hold(chan);
+ l2cap_chan_lock(chan);
+ if (sock_flag(sk, SOCK_DEAD)) {
+ err = -ENXIO;
+ goto done;
+ }
+

if (chan->mode == L2CAP_MODE_ERTM && !list_empty(&pi->rx_busy)) {
err = -ENOMEM;
@@ -1534,6 +1542,9 @@ static int l2cap_sock_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
}

done:
+ sock_put(sk);
+ l2cap_chan_unlock(chan);
+ l2cap_chan_put(chan);
release_sock(sk);

return err;